The entelechy is an Aristotelian notion, that also was picked up by Leibniz, whose monads are entelechies, and who believed absolutely everything - also what appears utterly lifeless - has some sort of entelechy that keeps it together to be that thing it is, and that keeps it doing the kinds of things entities of its kind do in given circumstances.

The most likely scientific hypothesis about animals and human beings is what corresponds to their entelechy is part of the functioning of their living brains, that is capable of representing some of the body and environment it is part of, in some ways.